1. Field of the Invention
The invention relates to a freewheel hub and through axle for bicycles, such as used for the wheel of the bicycle driven by a chain or the like. Such a hub transmits the driving force from the sprocket to the wheel while the bicyclist is pedaling, but allows free rotation of the wheel while the bicyclist is not pedaling.
2. Description of Prior Art
The basic design and functional requirements of the bicycle have existed for over one hundred years. However, the recent employment of the bicycle, particularly of the type BMX (Bicycle Moto-Cross), mountain bikes, off road tandems, and downhill racing, has greatly increased the demand for improved component performance. Even though the demand for higher performance has increased significantly, rear hub design has remained basically the same since the invention of the freewheel. Performance can be improved by reducing weight, increasing efficiency, or improving reliability.
The demands on rear hubs required by tandem teams have caused many failures of clutch mechanisms. Often tandem teams can weigh over 400 pounds, and can generate tremendous torque. Tandems are also being used off-road; and the terrain itself requires much more of the components. BMX and downhill racing also require a solid clutch mechanism due to the high momentary loads induced when a rider sprints.
Bicycles are being raced in the most inhospitable conditions. Often mountain bike races will take place in the snow, mud, and rain. Equipment is expected to perform flawlessly, race after race, with little maintenance. Most current designs have inadequate seals and require complete disassembly for cleaning and regreasing.
Most recently it has been recognized by frame designers that the rear hub, particularly the axle, can be an integral part of the bicycle frame. Many rear suspension designs are not adequately braced, and when standard hubs are used can experience instability and even catastrophic failure.